Ipriflavone Monograph

Ipriflavone O Monograph

CH3

H3C OO Ipriflavone Introduction Ipriflavone (IP), chemical structure 7- isopropoxyisoflavone, is an isoflavone, synthesized from the soy isoflavone, daidzein. It holds great promise in the prevention and treatment of osteoporosis and other metabolic bone diseases. Ipriflavone was discovered in the 1930s but has only recently begun to be embraced by the medical community in this country. Over 150 studies on safety and effectiveness, both animal and human, have been conducted in Italy, Hungary, and Japan. As of 1997, 2,769 patients had been treated for a total of 3,132 patient years.1

Pharmacokinetics Ipriflavone is metabolized mainly in the liver and excreted in the urine. Food appears to enhance its absorption. When given to healthy male volunteers, 80 percent of a 200-mg dose of ipriflavone was absorbed when taken after breakfast.2 Ipriflavone metabolism was not found to be significantly different in elderly osteoporotic or mild kidney failure patients than in younger, healthy subjects.3 Studies using labeled IP in rats found it concentrated primarily in the gastrointestinal tract, liver, kid- neys, bones, and adrenal glands.3

Mechanisms of Action Anti-resorptive Mechanisms An animal study found ipriflavone inhibited parathyroid hormone-, vitamin D-, PGE2-, and interleukin 1§-stimulated bone resorption.4 Bonnuci et al found parathyroid-stimulated osteoclastic activity and resulting hypercalcemia were inhibited in a dose-dependent manner by ipriflavone supple- mentation in rats.5

Bone-forming Mechanisms An in vitro examination of the osteoblastic effect of ipriflavone and its metabolites resulted in interesting findings. Ipriflavone and one of its metabolites stimulated cell proliferation of an osteo- blast-like cell line (UMR-106a Ð a cell line often used to determine the effect of various hormones and drugs on bone metabolism). IP and another metabolite increased alkaline phosphatase activity, while another metabolite enhanced collagen formation; IP alone inhibited parathyroid hormone activity.6

Lack of Direct Estrogen Effect One of the benefits of ipriflavone in the treatment of osteoporosis is its lack of direct estrogenic effect. Melis et al administered ipriflavone or placebo to a group of 15 postmenopausal women. LH, FSH, prolactin, and estradiol were measured after a single oral dose of 600 or 1000 mg, and after 7, 14, and 21 days of treatment with 600 or 1000 mg doses. No differences in endocrine effect were noted

between the ipriflavone and placebo groups. Vaginal cytology was unchanged after 21 days of IP or placebo compared to a significant increase in superficial vaginal cells in the estrogen group.7 In vitro investigation of the interaction between ipriflavone and preosteoclastic cell lines found it was not mediated by direct interaction with estrogen receptors.8 Instead, unique binding sites for ipriflavone were identified in the nucleus of preosteoclastic cells. The presence of IP binding sites was confirmed by Miyauchi et al. They identified two classes of binding sites in chicken osteoclasts and their precursors.9 Similar ipriflavone binding sites have been identified in human leukemic cells, a line with similar characteristics to osteoclast precursors. While ipriflavone does not have a directly estrogenic effect, it appears to potentiate its effect. Calcitonin secretion is modulated by estrogen and, while ipriflavone alone did not enhance calcitonin levels, it acted synergistically with estrogen, necessitating lower doses of estrogen to achieve normal calcitonin secretion. It appears IP increases the sensitivity of the thyroid gland to estrogen-stimulated calcitonin secretion.10

Therapeutics In the last decade there have been over 60 human studies Ð many double-blind and placebo- controlled Ð on the use of ipriflavone for the prevention and reversal of bone loss. An overview of these studies follows.

Postmenopausal Osteoporosis Ipriflavone has been studied in numerous double-blind, placebo controlled trials conducted in Italy, Hungary, and Japan. The same protocol was used throughout most of the studies Ð 200 mg ipriflavone or placebo three times daily. In most of the studies, calcium (500-1000 mg) was given to both ipriflavone and placebo groups. Several two-year studies looked at women immediately postmenopause (age 50-65) and found bone mass was maintained or improved slightly in the ipriflavone groups while those in the placebo groups experienced significant bone loss.11-14 It appears ipriflavone may be particularly effective for the treatment of so-called “senile osteoporosis” (osteoporosis in women or men over the age of 65) as evidenced by the results of two studies in seven Italian centers.1,15 In these studies a total of 112 subjects aged 65-79 were followed for two years. Subjects took either 600 mg ipriflavone plus 1 gram calcium daily or placebo plus 1 gram calcium. A four- to six-percent increase in bone density was observed in the ipriflavone groups, whereas the placebo groups experienced as much as a three-percent decrease in bone density. The most clini- cally relevant finding in the larger of the two studies was a decrease in fracture rates in the IP group (2 of 41 patients experienced fractures in the IP group, whereas 11 of 43 experienced fractures in the placebo group).1

Ipriflavone for Osteoporosis in Combination with Other Nutrients or Medications Ipriflavone has been found to enhance the effect of other bone-preserving agents, including 1α vitamin D (a form commonly used in Japan for osteoporosis).16 A number of studies have examined the effect of ipriflavone and estrogen for the treatment of osteoporosis. While low doses of conjugated estrogen (0.15-0.30 mg/day) typically are high enough to prevent hot flashes and other neurovegetative symptoms of menopause, a somewhat higher dose (0.625 mg/day or higher) is generally necessary for bone protection. Some studies, however, have found that when combining ipriflavone and estrogen, lower doses of estrogen afford protection.17-19

Alternative Medicine Review ◆ Volume 5, Number 3 ◆ 2000 Page 261 Copyright©2000 Thorne Research, Inc. All Rights Reserved. No Reprint Without Written Permission Ipriflavone versus Salmon Calcitonin An open, controlled 12-month trial compared ipriflavone with salmon calcitonin in 40 postmenopausal women. Significant increases in bone density were observed in both groups after 12 months: a 4.3-percent increase in BMD in the ipriflavone group and a 1.9-percent increase in the calcitonin group.20

Ipriflavone in the Prevention of Surgical or Drug-induced Osteoporosis Researchers examined the effect of ipriflavone in restraining bone loss induced by gonadotro- pin hormone-releasing hormone agonists (GnRH-A) such as Lupron, used to induce ovarian atrophy for the treatment of endometriosis, uterine fibroids, etc. In a double-blind, placebo-controlled trial 78 women treated with GnRH-A (3.75 mg leuproreline every 30 days for six months) were randomly assigned to receive either ipriflavone (600 mg/day) or placebo; both groups received 500 mg calcium daily. In placebo subjects, markers of bone turnover (urinary hydroxyproline and plasma bone Gla) were significantly elevated while BMD decreased significantly after six months. Conversely, there were no changes in BMD or bone markers in the ipriflavone-treated group.21 Animal studies have found ipriflavone inhibited bone loss associated with long-term steroid use22 and immobilization.23,24

Ipriflavone in the Treatment of Other Conditions There are several other pathological conditions involving bone which may be helped by ipriflavone. These include Paget’s disease of the bone,25 hyperparathyroidism,26 otosclerosis,27 and renal osteodystrophy.28

Safety In general, ipriflavone appears to be quite safe and well tolerated. As of 1997, long-term safety of ipriflavone (for periods ranging from 6-96 months) had been assessed in 2,769 patients for a total of 3,132 patient years in 60 human studies.1 The incidence of adverse reactions in the ipriflavone-treated patients was 14.5 percent, while the incidence in the placebo groups was 16.1 percent. Side-effects were mainly gastrointestinal (GI). Since the placebo groups in most studies received calcium, it is not unreasonable to assume calcium may have as much to do with GI effects as ipriflavone. Other symptoms observed to a lesser extent include skin rashes, headaches, depression, drowsiness, and tachycar- dia. Minor transient abnormalities in liver, kidney, and hematological parameters were documented in a small percent of subjects.

References 1. Agnusdei D, Bufalino L. Efficacy of ipriflavone in established osteoporosis and long-term safety. Calcif Tissue Int 1997;61:S23-S27. 2. Saito AM. Pharmacokinetic study of ipriflavone (TC80) by oral administration in healthy male volunteers. Jpn Pharm Ther J 1985;13:7223-7233. 3. Reginster JYL. Ipriflavone pharmacological properties and usefulness in postmenopausal osteoporosis. Bone Miner 1993;23:223-232. 4. Tsutsumi N, Kawashima K, Nagata H, et al. Effects of KCA-098 on bone metabolism: comparison with those of ipriflavone. Jpn J Pharmacol 1994;65:343-349. 5. Bonucci E, Ballanti P, Martelli A, et al. Ipriflavone inhibits osteoclast differentiation in parathyroid transplanted parietal bone of rats. Calcif Tissue Int 1992;50:314-319.

6. Benvenuti S, Tanini A, Frediani U, et al. Effects of ipriflavone and its metabolites on a clonal osteoblastic cell line. J Bone Miner Res 1991;6:987-996. 7. Melis GB, Paoletti AM, Cagnacci L, et al. Lack of any estrogenic effect of ipriflavone in postmenopausal women. J Endocrin Invest 1992;15:755-761. 8. Petilli M, Fiorelli G, Benvenuti U, et al. Interactions between ipriflavone and the estrogen receptor. Calcif Tissue Int 1995;56:160-165. 9. Miyauchi A, Notoya K, Taketomi S, et al. Novel ipriflavone receptors coupled to calcium influx regulate osteoclast differentiation and function. Endocrinology 1996;137:3544-3550. 10. Yamazaki I, Kinoshita M. Calcitonin secreting property of ipriflavone in the presence of estrogen. Life Sci 1986;38:1535-1541. 11. Adami S, Bufalino L, Cervetti R, et al. Ipriflavone prevents radial bone loss in postmenopausal women with low bone mass over 2 years. Osteoporos Int 1997;7:119-125. 12. Gennari C, Adami S, Agnusdei D, et al. Effect of chronic treatment with ipriflavone in postmenopausal women with low bone mass. Calcif Tissue Int 1997;61:S19-S22. 13. Agnusdei D, Crepaldi G, Isaia G, et al. A double blind, placebo-controlled trial of ipriflavone for prevention of postmenopausal spinal bone loss. Calcif Tissue Int 1997;61:142-147. 14. Valente M, Bufalino L, Castiglione GN, et al. Effects of 1-year treatment with ipriflavone on bone in postmenopausal women with low bone mass. Calcif Tissue Int 1994;54:377-380. 15. Passeri M, Biondi M, Costi D, et al. Effect of ipriflavone on bone mass in elderly osteoporotic women. Bone Miner 1992;19:S57-S62. 16. Ushiroyama T, Okamura S, Ikeda A, Ueki M. Efficacy of ipriflavone and 1a vitamin D therapy for the cessation of vertebral bone loss. Int J Gynaecol Obstet 1995;48:283-288. 17. Melis GB, Paoletti AM, Bartolini R, et al. Ipriflavone and low doses of estrogen in the prevention of one mineral loss in climacterium. Bone Miner 1992;19:S49-S56. 18. Gambacciani M, Ciaponi M, Cappagli B, et al. Effects of combined low dose of the isoflavone derivative ipriflavone and estrogen replacement on bone mineral density and metabolism in postmenopausal women. Maturitas 1997;28:75-81. 19. Agnusdei D, Gennari C, Bufalino L. Prevention of early postmenopausal bone loss using low doses of conjugated estrogens and the non-hormonal, bone-active drug ipriflavone. Osteoporos Int 1995;5:462-466. 20. Cecchettin M, Bellometti S, Cremonesi G, et al. Metabolic and bone effects after administration of ipriflavone and salmon calcitonin in postmenopausal osteoporosis. Biomed Pharmacother 1995;49:465-468. 21. Gambacciani M, Cappagli B, Piagessi L, et al. Ipriflavone prevents the loss of bone mass in pharmacological menopause induced by GnRH-agonists. Calcif Tissue Int 1997;61:15-18. 22. Yamazaki I, Shino A, Shimizu Y, et al. Effect of ipriflavone on glucocorticoid-induced osteoporosis in rats. Life Sci 1986;38:951-958. 23. Notoya K, Yoshia K, Tsukuda R, et al. Increase in femoral bone mass by ipriflavone alone and in combination

with 1α-hydroxyvitamin D3 in growing rats with skeletal unloading. Calcif Tissue Int 1996;58:88-94. 24. Foldes I, Rapcsak M, Szoor A, et al. The effect of ipriflavone treatment on osteoporosis induced by immobilization. Acta Morphologica Hungarica 1988;36:79-93. 25. Agnusdei D, Camporeale A, Gonnelli S, et al. Short-term treatment of Paget’s disease of bone with ipriflavone. Bone Miner 1992;19:S35-S42. 26. Mazzuoli G, Romagnoli E, Carnevale V, et al. Effects of ipriflavone on bone remodeling in primary hyperparathyroidism. Bone Miner 1992;19:S27-S33. 27. Sziklai I, Komora V, Ribari O. Double-blind study of the effectiveness of a bioflavonoid in the control of tinnitus in otosclerosis. Acta Chirurgica Hungarica 1992-93;33:101-107. 28. Hyodo T, Ono K, Koumi T, et al. A study of the effects of ipriflavone administration in hemodialysis patients with renal osteodystrophy: preliminary report. Nephron 1991;58:114-115.